Selective stripper mechanism

ABSTRACT

An improved punch press includes a selectively operable stripper unit which presses a workpiece against a lower turret as a tool is retracted away from the workpiece by a ram. A transfer device transmits actuating forces to the stripper unit during an operating cycle of the punch press. To enable the stripper unit to be selectively operated, the transfer device is operable between an active condition in which it is effective to transmit actuating forces to the stripper unit and an inactive condition in which the transfer device is ineffective to transmit actuating forces. A control apparatus initiates a punching operation only after the transfer device has been operated to either the active or inactive condition.

United States Patent 1 Dietrick et al.

[111 3,733,944 [451 May22, 1973 [54] SELECTIVE STRIPPER- MECHANISM [75]Inventors: Eugene Lewis Dietrick, Norristown;

Joseph Anthony Linkus, Levittown, both of Pa.

[22] Filed: Oct. 12, 1971 [21] Appl. No.: 188,393

[52] US. Cl. ..83/62, 83/71, 83/129,

uu i IHI l 11107111135 (4% 6/1969 Daniels...... ..83/552X ll/l970Killaly ..83/l40 Primary Examiner-Andrew R. Juhasz AssistantExaminer-Horace M. Culver Attorney-J. Herman Yount, Jr. et al.

[57] ABSTRACT An improved punch press includes a selectively operablestripper unit which presses a workpiece against a lower turret as a toolis retracted away from the workpiece by a ram. A transfer devicetransmits actuating forces to the stripper unit during an operatingcycle of the punch press. To enable the stripper unit to be selectivelyoperated, the transfer device is operable between an active condition inwhich it is effective to transmit actuating forces to the stripper unitand an inactive condition in which the transfer device is ineffective totransmit actuating forces. A control apparatus initiates a punchingoperation only after the transfer device has been operated to either theactive or inactive condition.

18 Claims, 4 Drawing Figures PATENTEU 2 2197s SHEET 2 OF 2 FIG.2

mvo STR/PPfQ (3 01V 7' WA S SELECTIVE STRIPPER MECHANISM The presentinvention relates to a new and improved stripper mechanism and morespecifically to a stripper mechanism having a stripper unit which can berendered effective or ineffective during operation of a machine tool.

A known punch press has a stripper mechanism for pressing a workpieceagainst a support surface as a punch or tool is retracted from theworkpiece. This known stripper mechanism is operated on each cycle ofthe punch press. However, there are certain operating conditions whereit is desirable to render the stripper mechanism ineffective.

Accordingly, it is an object of the present to provide a new andimproved stripper mechanism which is selectively operable between aneffective condition and an ineffective condition in accordance with theoperating demands placed on a machine.

Another object of this invention is to provide a new and improvedmachine having a stripper unit which is selectively operable between aneffective condition in which the stripper unit presses a workpieceagainst a support surface as a tool is retracted from the workpiece andan ineffective condition in which the stripper unit is ineffective topress the workpiece against the support surface as the tool isretracted.

Another object of this invention is to provide a new and improved turretpunch press for performing work operations on a workpiece with a tooland including a selectively operable stripper unit which is mounted onan upper turret of the punch press and is actuatable to press aworkpiece against a support surface on the lower turret as a tool isretracted from the workpiece by a ram, a transfer apparatus which maytransmit actuating forces from the ram to the stripper unit during anoperating cycle of the press, and wherein the transfer apparatus isoperable between an active condition in which it is effective totransmit actuating forces from the ram to the stripper unit to renderthe stripper unit effective to press the workpiece against the lowerturret as the tool is retracted and an inactive condition in which thetransfer apparatus is ineffective to transmit actuating forces from theram to the stripper unit to render the stripper unit ineffective topress the workpiece against the lower turret as the tool is retracted.

These and other objects and features of the present invention willbecome more apparent upon a consideration of the following descriptiontaken in connection with the accompanying drawings wherein:

FIG. 1 is a fragmentary illustration of a punch press having a strippermechanism constructed in accordance with the present invention;

FIG. 2 is a fragmentary sectional view, taken along the line 22 of FIG.1, illustrating the stripper mechanism in an active condition in whichthe stripper mechanism is effective to press a workpiece against asupport surface as a tool is retracted from the workpiece;

FIG. 3 is a fragmentary plan view, generally similar to FIG. 2,illustrating the stripper mechanism in an inactive condition in which itis ineffective to press a workpiece against a support surface as a toolis retracted; and

FIG. 4 is a schematic illustration of control circuitry for the punchpress of FIG. 1.

Although it is contemplated that an improved stripper mechanismconstructed in accordance with the present invention can be utilized inassociation with many different types of machine tools, it isillustrated in FIG. 1 in association with a tape-controlled turret punchpress 12. In accordance with conventional practice, the turret punchpress 12 has selectively rotatably upper and lower turrets l4 and 16.The lower turret 16 defines a support surface 20 on which a workpiece 22is disposed. During operation of the punch press 12, a hole is punchedin the workpiece 22 by a punch or tool 26 which passes through theworkpiece into a die or opening 28 in the lower turret 16. The punch 26is pressed downwardly by a ram 30 which is activated in a suitablemanner, such as by a known drive train which includes a crankshaft,clutch, and drive motor.

The striper mechanism 10 includes a stripperholddown unit 34 whichengages an upper surface of the workpiece 22 to press the workpieceagainst the lower turret 16 as the punch 26 is retracted. A stripperplate or member 36 of the stripper unit 34 engages the workpiece 22 andhas a central opening 38 through which the punch 26 passes. Thecross-sectional configuration of the opening 38 is the same as thecrosssectional configuration of the punch 26.

To enable the stripper plate 36 to move into and out of engagement withthe workpiece 22, the stripper plate is resiliently mounted on the upperturret 14 by a plurality of stripper pins 40 which are biased upwardlyby springs 42. The springs 42 urge the stripper plate 36 upwardlyagainst the lower surface of the turret 14. When the ram-30 is loweredor extended to force the punch 26 through the workpiece 22, the stripperplate 36 is pressed downwardly into engagement with the workpiece 22under the influence of forces transferred from the ram 30 by a stripperactuator assembly 46 and a selectively operable transfer assembly 48which is disposed between the actuator assembly 46 and thestripper-holddown unit 34. After the ram 30 has been retracted through asufficient distance to move the punch 26 out of engagement with theworkpiece 22, the biasing springs 42 are effective to return thestripper-holddown unit 34 to the retracted condition of FIG. 1.

Upon initiation of a punching operation, upper and lower spring plates52 and 54 in the stripper actuator assembly 46 are moved downwardly withthe ram 30 so that the lower spring plate 54 engages a plurality oftransfer pins 60 in the transfer assembly 48. Continued downwardmovement of the ram 30 presses the transfer pins 60 against theinfluence of biasing springs 62 so that the transfer pins move axiallyinto abutting engagement with guide pins 66 which are slidably disposedin bushings 68 in a punch press drive head 70. Still further downwardmovement of the ram 30 presses a drive plate or member 74, which isslidably mounted on the ram 30, against the stripper pins 40. Thus, asolid link or connection is formed between the lower spring plate 54 ofthe actuator assembly 46 and the stripper plate 36 by the transfer pins60, guide pins 66, drive plate 74 and stripper pins 40.

Continued downward movement of the ram 30 re-- sults in the stripperplate 36 being pressed against the upper surface of the workpiece 22. Itshould be noted that the leading or lower end 78 of the punch 26 followsor lags behind the leading or lower surface 80 of the stripper plate 36.Therefore, the stripper plate 36 engages the workpiece 22 and presses itagainst the lower turret 16 before punch 26 engages the workpiece.

Once the stripper plate 36 has moved into pressure engagement with theworkpiece 22, the stripper actuator assembly 46 is resilientlycompressed so that relative movement occurs between the punch 26 andstripper plate 36. This relative movement enables the punch 26 to passthrough the workpiece 22 into the opening 28 while the workpiece ispressed against the lower turret 16 by stripper plate 36.

To enable relative movement to occur between the punch 26 and stripperplate 36, the stripper actuator assembly 46 is compressed under theinfluence of forces transmitted between the stripper plate 36 and thelower spring plate 54 of actuator assembly by the stripper pins 40 andtransfer device 48. Thus, the lower spring plate 54 is slidably mountedon the ram 30, by a bushing 86. The upper spring plate 52 is fixedlyconnected with the ram 30 and is movable downwardly toward the lowerspring plate 54 against the influence of biasing springs 90 disposedbetween the upper and lower spring plates on guide members or pins 92.It should be noted that the biasing springs 90 are somewhat stiffer thanthe stripper pin biasing springs 42 and transfer pin biasing springs 62so that relative movement occurs between the spring plates 52 and 54only after the transfer pins 60 and stripper pins 40 have been movedaxially relative to the lower turret 14 under the influence of forcestransmitted from the ram 30 by the actuator assembly 46.

After a hole has been punched in the workpiece 22, the ram 30 isretracted. During initial retraction of the ram 30, the workpiece 22 ispressed downwardly against the lower turret 16 to strip the workpiecefrom the punch 26 as it is withdrawn. Thus, as the ram 30 begins itsupward stroke, the upper spring plate 52 moves upwardly away from thelower spring plate 54 with a relaxing of the springs 90. As the springs90 are relaxed they urge the lower plate 54 downwardly with sufficientforce to press the stripper plate 36 firmly against the workpiece 22.Therefore, the stripper biasing springs 42 and transfer biasing springs62 remain compressed under the influence of forces transmitted to thestripper plate 36 by transfer pins 60, guide pins 66, drive plate 74 andstripper pins 40.

When the upper spring plate 52 moves into engagement with stops or heads98 on the guide pins 92, the leading end 78 of the punch 26 has beenretracted past the leading surface 80 of the striper plate 36.Therefore, the workpiece 22 will have been completely stripped from thepunch 26. Further upward movement of the ram 30 results in both theupper and lower spring plates 52 and 54 being moved upwardly togetheraway from the lower turret 16. This releases the stripper plate 36 tomove upwardly, under the influence of the springs 42, into engagementwith the upper turret l4. Continued retraction of the ram 30 will resultin the transfer pins 60 being moved axially upwardly under the influenceof the springs 62 to the position shown in FIG. 1. Finally, the lowerspring plate 54 is moved away from the upper ends of the transfer pins60.

In accordance with a feature of the present invention, the strippermechanism is selectively operable between an effective condition inwhich the stripper plate 36 presses the workpiece 22 against the lowerturret 16 as the punch 26 is retracted and an ineffective condition inwhich the stripper plate does not press the workpiece against the lowerturret as the punch is retracted. To effect operation of the strippermechanism between the effective and ineffective conditions, the transferdevice 48 is selectively operable between an active condition (FIG. 2)in which it is effective to transmit forces from the stripper actuatorassembly 46 to the stripperholddown unit 34 and an inactive condition(FIG. 3) in which the transfer device 48 is ineffective to transmitforces from the stripper actuator assembly 46 to the stripper-holddownunit 34. The transfer device 48 is operated between the active conditionof FIG. 2 and the inactive condition of FIG. 3 by a piston and cylinderassembly 102.

When the transfer device 48 is in the active condition, the transferpins 60 are in axial alignment with the guide pins 66 (as shown inFIG. 1) to transmit forces from the actuator assembly 46 to the guidepins 66 and stripper-holddown unit 34. The transfer device 48 isoperated to the inactive condition by extending the piston cylinder 102to move the transfer pins 60 transversely to the inactive position ofFIG. 3 in which the transfer pins are axially offset relative to theguide pins 66. When the transfer device 48 is in the inactive conditionof FIG. 3, downward movement of the lower spring plate 54 merely pressesthe transfer pins 60 axially downwardly into holes 108 formed in thepress drive head 70. Therefore, this downward movement of the transferpins 60 is ineffective to move the guide pins 66 and drive plate 74downwardly to extend the stripper plate 36 against the influence of thesprings 42.

To provide for movement of the transfer pins 60 between the activeposition of FIGS. 1 and 2 and the inactive position of FIG. 3, thetransfer pins are slidably disposed in bushings 112 on a transfer plate114 which is rotatably mounted on a ram bushing 116. The transfer plate114 has an actuator arm 118 which is pivotally connected with a pistonrod 120 of the piston and cylinder assembly 102. Thus when the pistonand cylinder assembly 102 is operated from the retracted position ofFIG. 2 to the extended position of FIG. 3, the transfer plate 114 isrotated about the longitudinal axis of the ram 30 to move the transferpins 60 into axial alignment with the holes 108 in the drive head 70.When the transfer pins 60 are positioned in axial alignment with holes108, the transfer device 48 is ineffective to transmit force from thestripper actuator assembly 46 to the striper-holddown device 34 so thatthe stripper plate 36 remains in the retracted position (shown inFIG. 1) as the ram 30 and punch 26 are extended. Of course when thepiston and cylinder assembly 103 is retracted, the transfer plate 114 isrotated from the position shown in FIG. 3 to the position shown in FIG.2 to move the transfer pins 60 back into axial alignment with the guidepins 66. A screw or pin 124, which is fixedly connected with the drivehead 70 and extends into an arcuate slot 126 in the transfer plate 114,guides movement of the transfer plate between the active position ofFIG. 2 and the inactive position of FIG. 3.

Numerical controls 130 (FIG. 4) are provided to effect automaticoperation of turret indexing and stripper controls 132. The numericalcontrols 130 include a known reader 134 for a tape 136. During operationof the punch press 12, the stripper mechanism 10 is operated between theeffective and ineffective conditions in accordance with a predeterminedprogram on the tape 136. Accordingly, signals are transmitted from thetape reader 134 to numerical controls 138 for the punch press 12 toindicate whether the stripper mechanism 10 is to be rendered effectiveor ineffective during a particular punching operation.

The numerical controls 138 activate ram controls 142 in accordance withthese signals to activate the piston and cylinder assembly 102 when thestripper mechanism is to be operated between the ineffective andeffective condition between successive punching operations. To preventoperation of the punch press 12 when the transfer assembly 48 has beenonly partially actuated between the active position of FIG. 2 andinactive position of FIG. 3 and to provide an indication of the positionof the transfer assembly, detector switches 150 and 152 are mounted onthe press drive head 70 (see FIGS. 2 and 3) to sense the position of thetransfer plate 1 14 relative to the press drive head. Thus when thetransfer plate 114 is in the active position of FIG. 2, the normallyopen limit switch 152 is closed by a cam 154 mounted on the transferplate 114. Similarly when the transfer plate 114, is in the inactiveposition of FIG. 3, the normally open limit switch 150 is closed by acam 158 on the transfer plate 114. The detector switches 150 and 152cooperate with the ram controls 142 (see FIG. 4) to provide an interlockwhich renders the punch press 12 incapable of initiating a punchingoperation until one of the detector switches, that is either detectorswitch 150 or 152, is closed. Of course, the particular limit switch 150or 152 which must be closed will depend upon the program punched in thetape 136.

From the foregoing, it can be seen that the present invention provides'astripper mechanism 10 which is selectively operable between an activeposition and in which the striper mechanism is effective to press aworkpiece 22 against a support surface as the punch 26 is withdrawn fromthe workpiece and an inactive position in which the stripper mechanismis ineffective to press the workpiece against the support surface as thepunch is retracted. To effect operation of the stripper mechanism 10between the effective and ineffective conditions, a piston and cylinderassembly 102 is operable to rotate a transfer plate 114 to move transferpins 60 between an active position in which they are in axial alignmentwith guide pins 66 to transmit force from the stripper actuator assembly46 to the stripper-holddown device 34 and an inactive position in whichthe transfer pins are axially offset relative to the guide pins 66. Inthe inactive position, the transfer pins 60 are ineffective to transmitforce from a stripper actuator assembly 46 to the striper-holddown unit34. Operation of the stripper mechanism 10 between the effective andineffective conditions is advantageously controlled by numericalcontrols 130 for the punch press 12 in accordance with a predeterminedprogram on a punch tape 136.

Although the transfer assembly 48 is illustrated herein in associationwith the guide pins 66 and drive plate 74, it is contemplated that theguide pins and drive plate could be omitted and the stripper pins 40driven directly by the transfer pins 60. In addition, it should beunderstood that although the stripper mechanism 10 has been illustratedherein in association with a tape-controlled turret punch press 12, itshould be understood that the stripper mechanism could be associatedwith other types of machines having different types of controls.

It should be understood that although only a'single punch 26 and die 28have been illustrated in the drawings, it is contemplated that aplurality of punches will be mounted on the upper turret 14 inassociated with a plurality of dies on the lower turret 16 in accordancewith common practice. Thus, a plurality of stripper units 34 will beprovided on the upper turret 14. Each of these stripper units will beassociated with one punch 26 of the plurality of punches. Upon rotationof the upper and lower turrets l4 and 16, each punch and stripper unitwill be moved in turn into cooperating relationship with the ram 30.Therefore, the same stripper actuator assembly 46 and transfer assembly48 can be utilized to sequentially activate a plurality of stripperunits 34. Of course, the transfer assembly 48 will be indexed to theinactive condition when the prepunched program on the tape 136 indicatesthat a particular stripper unit is'to remain inactive during a punchingoperation.

Having described a specific preferred embodiment of the invention, thefollowing is claimed:

1. A machine for performing work operations on a workpiece with a tool,said machine comprising a workpiece support surface, ram means formoving the tool through an operating cycle which includes moving thetool into engagement with the workpiece and retracting the tool from theworkpiece, selectively operable stripper means associated with said rammeans for pressing the workpiece against said support surface as thetool is retracted from the workpiece by said ram means, transfer meansoperable between an active condition in which said transfer means iseffective to transmit actuating forces to said stripper means and aninactive condition in which said transfer means is ineffective totransmit actuating forces to said stripper means to render said strippermeans ineffective to press the workpiece against said workpiece supportsurface as the tool is retracted, and actuator means for effectingoperation of said transfer means between the active condition and theinactive condition.

2. A machine as set forth in claim 1 wherein said transfer meansincludes a plurality of actuator elements and mounting means forsupporting said actuator elements for movement in a first direction totransfer actuating forces to said stripper means, said actuator meansincluding means for moving said actuator elements in a second directiontransverse to said first direction to effect operation of said transfermeans between the active and inactive conditions.

3. A machine as set forth in claim 1 wherein said transfer means andstripper means include a plurality of sets of pins, said transfer meansincluding means for moving one of said sets of pins from a firstposition in which said one set of pins is axially aligned with anotherset of pins to a second position in which said one set of pins isaxially offset from said other set of pins upon operation of saidtransfer means from the active condition to the inactive condition.

4. A machine as set forth in claim 3 wherein said stripper meansincludes a stripper plate fixedly connected with one of said pluralityof sets of pins.

5. A machine as set forth in claim 1 further including control means forcontrolling the operation of said machine, said control means includingdetector means for detecting when said transfer means is in the inactivecondition and in the active condition, and interlock means forpreventing movement of the tool by said ram means when said detectormeans detects that said transfer means is in a condition other than theactive condition or the inactive condition.

6. A machine as set forth in claim 1 further including ram control meansfor controlling operation of said ram means, main control means foractivating said ram control means and interlock means for preventingactivation of said ram control means by said main control means whensaid transfer means is in a condition other than the active or inactiveconditions.

7. A turret punch press for performing work operations on a workpiecewith a tool, said punch press comprising a base, an upper turretrotatably mounted on said base, a lower turret rotatably mounted on saidbase and at least partially defining a workpiece support surface, rammeans for effecting relative movement between the tool and said upperand lower turrets to move the tool through an operating cycle whichincludes moving the tool into engagement with the workpiece andretracting the tool from the workpiece, selectively operable strippermeans mounted on said upper turret and actuatable under the influencesof forces transmitted to said stripper means from said ram means topress the workpiece against the workpiece support surface on said lowerturret as the tool is retracted from the workpiece by said ram means,transfer means operatively connected with said stripper means and saidram means forv transmitting actuating forces from said ram means to saidstripper means during an operating cycle of said punch press, saidtransfer means being operable between an active condition in which saidtransfer means is effective to transmit actuating forces from said rammeans to said stripper means to render said stripper means effective topress the workpiece against said workpiece support surface on said lowerturret as the tool is retracted and an inactive condition in which saidtransfer means is ineffective to transmit actuating forces from said rammeans to said stripper means to render said stripper means ineffectiveto press the workpiece against said workpiece support surface as thetool is retracted, actuator means for effecting operation of saidtransfer means between the active condition in which said stripper meansis effective to press the workpiece against said workpiece supportsurface during retraction of the tool and the inactive condition inwhich said stripper means is ineffective to press the workpiece againstsaid workpiece support surface during retraction of the tool, detectormeans for detecting when said transfer means has been operated to one ofsaid conditions, and control means for initiating operation of said rammeans to move the tool through an operating cycle only after detectionby said detector means that said transfer means is in either said activeor inactive condition.

8. A turret punch press as set forth in claim 7 wherein said strippermeans includes a stripper element disposed between said upper and lowerturrets and defining opening through which the tool passes to engage aworkpiece, a plurality of stripper support members fixedly connectedwith said stripper element and movably mounted on said upper turret, andstripper springs operatively interconnecting said stripper supportmembers and said lower turret to bias said stripper element upwardlyagainst said upper turret, said transfer means including resilient drivemeans for transmitting force from said ram means and for enabling saidram means to move relative to said stripper means when the workpiece ispressed against said support surface with a predetermined force by saidstripper means, a transfer member, and a plurality of transfer pinsmounted on said transfer member, said transfer pins being effective totransmit force between said drive means and said strippermeans when saidtransfer means is in the active condition, said transfer pins beingmovable axially relative to said stripper means by said drive means whensaid transfer means is in the inactive condition to thereby render saidtransfer pins ineffective to transmit forces between said drive meansand said stripper means.

9. A turret punch press as set forth in claim 7 wherein said controlmeans includes means for effecting operation of said transfer meansbetween the active and inactive conditions in. accordance with apredetermined program.

10. A turret punch press for performing work operations'on a workpiece,said punch press comprising a base, an upper turret rotatably mounted onsaid base, a plurality of punches mounted on said upper turret, a lowerturret rotatably mounted on said base and at least partially defining aworkpiece support surface, drive means for rotating said turrets to moveeach of the punches in turn to a work station, ram means at the workstation for effecting relative movement between one of the punches andsaid upper and lower turrets to move the one punch through an operatingcycle which includes moving the one punch into engagement with theworkpiece and retracting the one-punch from the workpiece, a pluralityof selectively operable stripper means mounted on said upper turret,each of said stripper means being associated with one of said punchesand being actuatable at the work station under the influences of forcestransmitted to the stripper means at the work station from said rammeans to press the workpiece against the workpiece support surface onsaid lower turret as the punch at the work station is retracted from theworkpiece by said ram means, transfer means operatively connected withsaid ram means for transmitting actuating forces from said ram means toeach of said stripper means in turn at the work station during operatingcycles of said punch press, said transfer means being operable betweenan active condition in which said transfer means is effective totransmit actuating forces from said ram means to a stripper means at thework station to render the stripper support surface on said lower turretas the punch at the work station is retracted and an inactive conditionin which said transfer means is ineffective to transmit actuating forcesfrom said ram means to the stripper means at the work station to renderthe stripper means at the work station ineffective to press theworkpiece against said workpiece support surface as the punch at thework station is retracted, actuator means for effecting operation ofsaid transfer means between the active condition in which the strippermeans at the work station is effective to press the workpiece againstsaid workpiece support surface during retraction of the punch at thework station and the inactive condition in which the stripper means atthe work station is ineffective to press the workpiece against saidworkpiece support surface during retraction of the punch at the'workstation, detector means for detecting when said transfer means has beenoperated to one of said conditions, and control means for initiatingoperation of said ram means to move a punch through an operating cycleonly after detection by said detector means that said transfer means isin either said active or inactive condition.

11. A turret punch press as set forth in claim wherein each of saidstripper means includes a stripper element disposed between said upperand lower turrets and defining opening through which an associated oneof said punches passes to engage a workpiece, a plurality of strippersupport members fixedly connected with said stripper element and movablymounted on said upper turret, and stripper springs operativelyinterconnecting said stripper support members and said lower turret tobias said stripper element upwardly against said upper turret, saidtransfer means including resilient drive means for transmitting forcefrom said ram means and for enabling said ram means to move relative tothe stripper means at the work station when the workpiece is pressedagainst said support surface with a predetermined force, a transfermember, and a plurality of transfer pins mounted on said transfermember, said transfer pins being effective to transmit force betweensaid drive means and the stripper means at the work station when saidtransfer means is in the active condition, said transfer pins beingmovable axially relative to the stripper means at the work station bysaid drive means when said transfer means is in the inactive conditionto thereby render said transfer pins ineffective to transmit forcesbetween said drive means and the stripper means at the work station.

12. A turret punch press as set forth in claim 10 wherein said controlmeans includes means for effecting rotation of said upper and lowerturrets to move one of said punches and the associated one of saidstripper means to the work station in accordance with a predeterminedprogram and means for effecting operation of said transfer means betweenthe active and inactive conditions in accordance with the predeterminedprogram.

13. A turret punch press for performing work operations on a workpiecewith a too], said punch press comprising a base, an upper turretrotatably mounted on said base, a lower turret rotatably mounted on saidbase and at least partially defining a workpiece support surface, rammeans for effecting relative movement between the tool and said upperandlower turrets to move the tool through an operating cycle whichincludes moving the tool into engagement with the workpiece andretracting the tool from the workpiece, selectively operable strippermeans mounted on said upper turret and actuatable under the influencesof forces transmitted to said stripper means from said ram means topress the workpiece against the workpiece support surface on said lowerturret as the tool is retracted from the workpiece by said ram means,transfer means operatively connected with said stripper means and saidram means for transmitting actuating forces from said ram means to saidstripper means during an operating cycle of said punch press, saidtransfer means being operable between an active condition in which saidtransfer means is effective to transmit actuating forces from said rammeans to said stripper means to render said stripper means effective topress the workpiece against said workpiece support surface on said lowerturret as the tool is retracted and an inactive condition in which saidtransfer means is ineffective to transmit actuating forces from said rammeans to said stripper means to render said stripper means ineffectiveto press the workpiece against said workpiece support surface as thetool is retracted, actuator means for effecting operation of saidtransfer means between the active condition in which said stripper meansis effective to press the workpiece against said workpiece supportsurface during retraction of the tool and the inactive condition inwhich said stripper means is ineffective to press the workpiece againstsaid workpiece support surface during retraction of the tool, andcontrol means for initiating operation of said ram means to move thetool through an operating cycle when said transfer means in in eithersaid active or inactive condition.

14. A turret punch press as set forth in claim 13 wherein said strippermeans includes a stripper element disposed between said upper and lowerturrets and defining opening through which the tool passes to engage aworkpiece, a plurality of stripper support members fixedly connectedwith said stripper element and movably mounted on said upper turret, andstripper springs operatively interconnecting said stripper supportmembers and said lower turret to bias said stripper element upwardlyagainst said upper turret, said transfer means including resilient drivemeans for transmitting force from said ram means and for enabling saidram means to move relative to said stripper means when the workpiece ispressed against said support surface with a predetermined force by saidstripper means, a transfer member, and a plurality of transfer pinsmounted on said transfer member, said transfer pins being effective totransmit force between said drive means and said stripper means whensaid transfer means is in the active condition, said transfer pins beingmovable axially relative to said stripper means by said drive means whensaid transfer means is in the inactive condition to thereby render saidtransfer pins ineffective to transmit forces between said drive meansand said stripper means.

15. A turret punch press as set forth in claim 13 wherein said controlmeans includes means for effecting operation of said transfer meansbetween the active and inactive conditions in accordance with apredetermined program.

16. A turret punch press for performing work operations on a workpiece,said punch press comprising-a base, an upper turret rotatably mounted onsaid base, a plurality of punches mounted on said upper turret, a lowerturret rotatably mounted on said base and at least partially defining aworkpiece support surface, drive means for rotating said turrets to moveeach of the punches in turn to a work station, ram means at the workstation for effecting relative movement between one of the punchesandsaid upper and lower turrets to move the one punch through anoperating cycle which includes moving the one punch into engagement withthe workpiece and retracting the one punch from the workpiece, aplurality of selectively operable stripper means mounted on said upperturret, each of said stripper means being associated with one of saidpunches and being actuatable at the work station under the influences offorces transmitted to the stripper means at the work station from saidram means to press the workpiece against the workpiece support surfaceon said lower turret as the punch at the work station is retracted fromthe workpiece by said ram means, transfer means operatively connectedwith said ram means for transmitting actuating forces from said rammeans to each of said stripper means in turn at the work station duringoperating cycles of said punch press, said transfer means being operablebetween an active condition in which said transfer means is effective totransmit actuating forces from said ram means to a stripper means at thework station to render the stripper support surface on said lower turretas the punch at the work station is retracted and an inactive conditionin which said transfer means is ineffective to transmit actuating forcesfrom said ram means to the stripper means at the work station to renderthe stripper means at the work station ineffective to press theworkpiece against said workpiece support surface as the punch at thework station is retracted, actuator means for effecting operation ofsaid transfer means between the active condition in which the strippermeans at the work station is effective to press the workpiece againstsaid workpiece support surface during retraction of the punch at thework station and the inactive condition in which the stripper means atthe work station is ineffective to press the workpiece against saidworkpiece support surface during retraction of the punch at the workstation, and control means for initiating operation of said ram means tomove a punch through an operating cycle when said transfer means is ineither said active or inactive condition.

17. A turret punch press as set forth in claim 16 wherein each of saidstripper means includes a stripper element disposed between said upperand lower turrets and defining opening through which an associated oneof said punches passes to engage a workpiece, a plurality of strippersupport members fixedly connected with said stripper element and movablymounted on said upper turret, and stripper springs operativelyinterconnecting said stripper support members and said lower turret tobias said stripper element upwardly against said upper turret, saidtransfer means including resilient drive means for transmitting forcefrom said ram means and for enabling said ram means to move relative tothe stripper means at the work station when the workpiece is pressedagainst said support surface with a predetermined force, a transfermember, and a plurality of transfer pins mounted on said transfer memher, said transfer pins being effective to transmit force between saiddrive means and the stripper means at the work station when saidtransfer means is in the active condition, said transfer pins beingmovable axially relative to the stripper means at the work station bysaid drive means when said transfer means is in the inactive conditionto thereby render said transfer pins ineffective to transmit forcesbetween said drive means and the stripper means at the work station.

18. A turret punch press as set forth in claim 16 wherein said controlmeans includes means for effecting rotation of said upper and lowerturrets to move one of said punches and the associated one of saidstripper means to the work station in accordance with a predeterminedprogram and means for effecting operation of said transfer means betweenthe active and inactive conditions in accordance with the predeterminedprogram.

1. A machine for performing work operations on a workpiece with a tool,said machine comprising a workpiece support surface, ram means formoving the tool through an operating cycle which includes moving thetool into engagement with the workpiece and retracting the tool from theworkpiece, selectively operable stripper means associated with said rammeans for pressing the workpiece against said support surface as thetool is retracted from the workpiece by said ram means, transfer meansoperable between an active condition in which said transfer means iseffective to transmit actuating forces to said stripper means and aninactive condition in which said transfer means is ineffective totransmit actuating forces to said stripper means to render said strippermeans ineffective to press the workpiece against said workpiece supportsurface as the tool is retracted, and actuator means for effectingoperation of said transfer means between the active condition and theinactive condition.
 2. A machine as set forth in claim 1 wherein saidtransfer means includes a plurality of actuator elements and mountingmeans for supporting said actuator elements for movement in a firstdirection to transfer actuating forces to said stripper means, saidactuator means including means for moving said actuator elements in asecond direction transverse to said first direction to effect operationof said transfer means between the active and inactive conditions.
 3. Amachine as set forth in claim 1 wherein said transfer means and strippermeans include a plurality of sets of pins, said transfer means includingmeans for moving one of said sets of pins from a first position in whichsaid one set of pins is axially aligned with another set of pins to asecond position in which said one set of pins is axially offset fromsaid other set of pins upon operation of said transfer means from theactive condition to the inactive condition.
 4. A machine as set forth inclaim 3 wherein said stripper means includes a stripper plate fixedlyconnected with one of said plurality of sets of pins.
 5. A machine asset forth in claim 1 further including control means for controlling theoperation of said machine, said control means including detector meansfor detecting when said transfer means is in the inactive condition andin the active condition, and interlock means for preventing movement ofthe tool by said ram means when said detector means detects that saidtransfer means is in a condition other than the active condition or theinactive condition.
 6. A machine as set forth in claim 1 furtherincluding ram control means for controlling operation of said ram means,main control means for activating said ram control means and interlockmeans for preventing activation of said ram control means by said maincontrol means when said transfer means is in a condition other than theactive or inactive conditions.
 7. A turret punch press for performingwork operations on a workpiece with a tool, said punch press comprisinga base, an upper turret rotatably mounted on said base, a lower turretrotatably mounted on said base and at least partially defining aworkpiece support surface, ram means for effecting relative movementbetween the tool and said upper and lower turrets to move the toolthrough an operating cycle which includes moving the tool intoengagement with the workpiece and retracting the tool from theworkpiece, selectively operable stripper means mounted on said upperturret and actuatable under the influences of forces transmitted to saidstripper means from said ram means to press the workpiece against theworkpiece support surface on said lower turret as the tool is retractedfrom the workpiece by said ram means, transfer means operativelyconnected with said stripper means and said ram means for transmittingactuating forces from said ram means to said stripper means during anoperating cycle of said punch press, said transfer means being operablebetween an active condition in which said transfer means is effective totransmit actuating forces from said ram means to said stripper means torender said stripper means effective to press the workpiece against saidworkpiece support surface on said loWer turret as the tool is retractedand an inactive condition in which said transfer means is ineffective totransmit actuating forces from said ram means to said stripper means torender said stripper means ineffective to press the workpiece againstsaid workpiece support surface as the tool is retracted, actuator meansfor effecting operation of said transfer means between the activecondition in which said stripper means is effective to press theworkpiece against said workpiece support surface during retraction ofthe tool and the inactive condition in which said stripper means isineffective to press the workpiece against said workpiece supportsurface during retraction of the tool, detector means for detecting whensaid transfer means has been operated to one of said conditions, andcontrol means for initiating operation of said ram means to move thetool through an operating cycle only after detection by said detectormeans that said transfer means is in either said active or inactivecondition.
 8. A turret punch press as set forth in claim 7 wherein saidstripper means includes a stripper element disposed between said upperand lower turrets and defining opening through which the tool passes toengage a workpiece, a plurality of stripper support members fixedlyconnected with said stripper element and movably mounted on said upperturret, and stripper springs operatively interconnecting said strippersupport members and said lower turret to bias said stripper elementupwardly against said upper turret, said transfer means includingresilient drive means for transmitting force from said ram means and forenabling said ram means to move relative to said stripper means when theworkpiece is pressed against said support surface with a predeterminedforce by said stripper means, a transfer member, and a plurality oftransfer pins mounted on said transfer member, said transfer pins beingeffective to transmit force between said drive means and said strippermeans when said transfer means is in the active condition, said transferpins being movable axially relative to said stripper means by said drivemeans when said transfer means is in the inactive condition to therebyrender said transfer pins ineffective to transmit forces between saiddrive means and said stripper means.
 9. A turret punch press as setforth in claim 7 wherein said control means includes means for effectingoperation of said transfer means between the active and inactiveconditions in accordance with a predetermined program.
 10. A turretpunch press for performing work operations on a workpiece, said punchpress comprising a base, an upper turret rotatably mounted on said base,a plurality of punches mounted on said upper turret, a lower turretrotatably mounted on said base and at least partially defining aworkpiece support surface, drive means for rotating said turrets to moveeach of the punches in turn to a work station, ram means at the workstation for effecting relative movement between one of the punches andsaid upper and lower turrets to move the one punch through an operatingcycle which includes moving the one punch into engagement with theworkpiece and retracting the one-punch from the workpiece, a pluralityof selectively operable stripper means mounted on said upper turret,each of said stripper means being associated with one of said punchesand being actuatable at the work station under the influences of forcestransmitted to the stripper means at the work station from said rammeans to press the workpiece against the workpiece support surface onsaid lower turret as the punch at the work station is retracted from theworkpiece by said ram means, transfer means operatively connected withsaid ram means for transmitting actuating forces from said ram means toeach of said stripper means in turn at the work station during operatingcycles of said punch press, said transfer means being operable betweenan active condition in which said transfer means is effective totransmit actUating forces from said ram means to a stripper means at thework station to render the stripper support surface on said lower turretas the punch at the work station is retracted and an inactive conditionin which said transfer means is ineffective to transmit actuating forcesfrom said ram means to the stripper means at the work station to renderthe stripper means at the work station ineffective to press theworkpiece against said workpiece support surface as the punch at thework station is retracted, actuator means for effecting operation ofsaid transfer means between the active condition in which the strippermeans at the work station is effective to press the workpiece againstsaid workpiece support surface during retraction of the punch at thework station and the inactive condition in which the stripper means atthe work station is ineffective to press the workpiece against saidworkpiece support surface during retraction of the punch at the workstation, detector means for detecting when said transfer means has beenoperated to one of said conditions, and control means for initiatingoperation of said ram means to move a punch through an operating cycleonly after detection by said detector means that said transfer means isin either said active or inactive condition.
 11. A turret punch press asset forth in claim 10 wherein each of said stripper means includes astripper element disposed between said upper and lower turrets anddefining opening through which an associated one of said punches passesto engage a workpiece, a plurality of stripper support members fixedlyconnected with said stripper element and movably mounted on said upperturret, and stripper springs operatively interconnecting said strippersupport members and said lower turret to bias said stripper elementupwardly against said upper turret, said transfer means includingresilient drive means for transmitting force from said ram means and forenabling said ram means to move relative to the stripper means at thework station when the workpiece is pressed against said support surfacewith a predetermined force, a transfer member, and a plurality oftransfer pins mounted on said transfer member, said transfer pins beingeffective to transmit force between said drive means and the strippermeans at the work station when said transfer means is in the activecondition, said transfer pins being movable axially relative to thestripper means at the work station by said drive means when saidtransfer means is in the inactive condition to thereby render saidtransfer pins ineffective to transmit forces between said drive meansand the stripper means at the work station.
 12. A turret punch press asset forth in claim 10 wherein said control means includes means foreffecting rotation of said upper and lower turrets to move one of saidpunches and the associated one of said stripper means to the workstation in accordance with a predetermined program and means foreffecting operation of said transfer means between the active andinactive conditions in accordance with the predetermined program.
 13. Aturret punch press for performing work operations on a workpiece with atool, said punch press comprising a base, an upper turret rotatablymounted on said base, a lower turret rotatably mounted on said base andat least partially defining a workpiece support surface, ram means foreffecting relative movement between the tool and said upper and lowerturrets to move the tool through an operating cycle which includesmoving the tool into engagement with the workpiece and retracting thetool from the workpiece, selectively operable stripper means mounted onsaid upper turret and actuatable under the influences of forcestransmitted to said stripper means from said ram means to press theworkpiece against the workpiece support surface on said lower turret asthe tool is retracted from the workpiece by said ram means, transfermeans operatively connected with said stripper means and said ram meansfor transMitting actuating forces from said ram means to said strippermeans during an operating cycle of said punch press, said transfer meansbeing operable between an active condition in which said transfer meansis effective to transmit actuating forces from said ram means to saidstripper means to render said stripper means effective to press theworkpiece against said workpiece support surface on said lower turret asthe tool is retracted and an inactive condition in which said transfermeans is ineffective to transmit actuating forces from said ram means tosaid stripper means to render said stripper means ineffective to pressthe workpiece against said workpiece support surface as the tool isretracted, actuator means for effecting operation of said transfer meansbetween the active condition in which said stripper means is effectiveto press the workpiece against said workpiece support surface duringretraction of the tool and the inactive condition in which said strippermeans is ineffective to press the workpiece against said workpiecesupport surface during retraction of the tool, and control means forinitiating operation of said ram means to move the tool through anoperating cycle when said transfer means in in either said active orinactive condition.
 14. A turret punch press as set forth in claim 13wherein said stripper means includes a stripper element disposed betweensaid upper and lower turrets and defining opening through which the toolpasses to engage a workpiece, a plurality of stripper support membersfixedly connected with said stripper element and movably mounted on saidupper turret, and stripper springs operatively interconnecting saidstripper support members and said lower turret to bias said stripperelement upwardly against said upper turret, said transfer meansincluding resilient drive means for transmitting force from said rammeans and for enabling said ram means to move relative to said strippermeans when the workpiece is pressed against said support surface with apredetermined force by said stripper means, a transfer member, and aplurality of transfer pins mounted on said transfer member, saidtransfer pins being effective to transmit force between said drive meansand said stripper means when said transfer means is in the activecondition, said transfer pins being movable axially relative to saidstripper means by said drive means when said transfer means is in theinactive condition to thereby render said transfer pins ineffective totransmit forces between said drive means and said stripper means.
 15. Aturret punch press as set forth in claim 13 wherein said control meansincludes means for effecting operation of said transfer means betweenthe active and inactive conditions in accordance with a predeterminedprogram.
 16. A turret punch press for performing work operations on aworkpiece, said punch press comprising a base, an upper turret rotatablymounted on said base, a plurality of punches mounted on said upperturret, a lower turret rotatably mounted on said base and at leastpartially defining a workpiece support surface, drive means for rotatingsaid turrets to move each of the punches in turn to a work station, rammeans at the work station for effecting relative movement between one ofthe punches and said upper and lower turrets to move the one punchthrough an operating cycle which includes moving the one punch intoengagement with the workpiece and retracting the one punch from theworkpiece, a plurality of selectively operable stripper means mounted onsaid upper turret, each of said stripper means being associated with oneof said punches and being actuatable at the work station under theinfluences of forces transmitted to the stripper means at the workstation from said ram means to press the workpiece against the workpiecesupport surface on said lower turret as the punch at the work station isretracted from the workpiece by said ram means, transfer meansoperatively connected with said ram means for transmitting actuatingforces from said ram means to each of said stripper means in turn at thework station during operating cycles of said punch press, said transfermeans being operable between an active condition in which said transfermeans is effective to transmit actuating forces from said ram means to astripper means at the work station to render the stripper supportsurface on said lower turret as the punch at the work station isretracted and an inactive condition in which said transfer means isineffective to transmit actuating forces from said ram means to thestripper means at the work station to render the stripper means at thework station ineffective to press the workpiece against said workpiecesupport surface as the punch at the work station is retracted, actuatormeans for effecting operation of said transfer means between the activecondition in which the stripper means at the work station is effectiveto press the workpiece against said workpiece support surface duringretraction of the punch at the work station and the inactive conditionin which the stripper means at the work station is ineffective to pressthe workpiece against said workpiece support surface during retractionof the punch at the work station, and control means for initiatingoperation of said ram means to move a punch through an operating cyclewhen said transfer means is in either said active or inactive condition.17. A turret punch press as set forth in claim 16 wherein each of saidstripper means includes a stripper element disposed between said upperand lower turrets and defining opening through which an associated oneof said punches passes to engage a workpiece, a plurality of strippersupport members fixedly connected with said stripper element and movablymounted on said upper turret, and stripper springs operativelyinterconnecting said stripper support members and said lower turret tobias said stripper element upwardly against said upper turret, saidtransfer means including resilient drive means for transmitting forcefrom said ram means and for enabling said ram means to move relative tothe stripper means at the work station when the workpiece is pressedagainst said support surface with a predetermined force, a transfermember, and a plurality of transfer pins mounted on said transfermember, said transfer pins being effective to transmit force betweensaid drive means and the stripper means at the work station when saidtransfer means is in the active condition, said transfer pins beingmovable axially relative to the stripper means at the work station bysaid drive means when said transfer means is in the inactive conditionto thereby render said transfer pins ineffective to transmit forcesbetween said drive means and the stripper means at the work station. 18.A turret punch press as set forth in claim 16 wherein said control meansincludes means for effecting rotation of said upper and lower turrets tomove one of said punches and the associated one of said stripper meansto the work station in accordance with a predetermined program and meansfor effecting operation of said transfer means between the active andinactive conditions in accordance with the predetermined program.